Method for the treatment of forms for molding concrete with wax emulsion release agent



United States Patent METHOD FOR THE TREATMENT OF FORMS FOR MOLDINGCONCRETE WITH WAX EMULSION RELEASE AGENT Marilyn J. Ekiss, Seattle,Wash., George A. Weisgerber,

Cranford, N.J., and Theodore F. Hand, Houston, Tex.,

assignors to Esso Research and Engineering Company,

a corporation of Delaware No Drawing. Filed June 21, 1962, Ser. No.204,088

11 Claims. (Cl. 264-338) This invention relates to a wax emulsion andits use as a concrete mold release agent. Particularly, the inventionrelates to a water emulsion of wax, which emulsion is useful for coatingrigid forms used for molding concrete.

A number of structures such as prestressed bridge slabs, pilings andpipe, building blocks, burial vaults, bridges, dams, housingfoundations, etc., are cast by pouring concrete into forms made ofsteel, wood, heavy cardboard, Masonite, plywood, etc., and then laterremoving the forms from the hardened concrete. To help reduce thesticking of the concrete to the forms, and to give easier release of theconcrete from the mold, a mold release agent is generally used. Anextremely wide variety of materials intended to serve as mold releaseagents have been used for this purpose, such as waterproof kraft orasphalt papers, shellac, lacquers, muslin, castor oil, mineral oil,crankcase drainings, compounded petroleum oils, etc. However, many ofthese materials have various deficiencies or are limited in their use.For example, paper or cloth leaves unwanted marks, especially if thematerial overlaps or wrinkles, While many of the oil type mold releaseagents leave stains or unwanted residual deposits. Other commondeficiencies are: soaking of the release agent in porous (e.g. wooden)mold forms, excessive run-01f or formation of non-uniform films,inconvenience or messy in application, inefiicient in preventingbonding, etc. On the other hand, the wax emulsions of the invention donot have these disadvantages while having many desirable properties.Thus, the wax emulsion type concrete form release agent of the inventioncan be applied to the form conveniently by spraying or painting and willspread to a uniform thin film. Wasteful over-application, which isnecessary with some release agents, is avoided. After application of thethin film, it will set up rather quickly by evaporation of the water,leaving a moderately hard protective layer, and will not stain theadjacent concrete surface.

Mold release agents of this invention are prepared by emulsifyingcertain types of petroleum waxes into water. Specifically, suitablewater emulsions can contain about 2 to Wt. percent wax and about 0.1 to5.0 wt. percent of emulsifying agent. Preferred compositions contain 5to 25 wt. percent wax, and 0.5 to 3.0 wt. percent of emulsifying agent.For convenience of handling, these emulsions are preferably made up inthe form of concentrates containing about 20 to wax and about 1 to 8 wt.percent emulsifying agent, and are later diluted with additional Waterbefore use by simple mixing.

The waxes used in the mold release composition of this invention includepetroleum waxes having melting points (-EMP) of to 185 F., preferably to165 stocks, etc. These waxes usually contain less than 5 wt. percentoil, and preferably contain less than 2 wt. percent oil.Microcrystalline wax differs from paraflin wax in that it contains asubstantial portion of branched chain hydrocarbon and the hydrocarbonsare of highermolecular weight. Microcrystalline waxes are generally moreplastic than refined paraffin waxes and generally have melting points ofabout to 185 F; 7

Instead of using refined paraffin wax, various crude paraffin waxeshaving higher oil contents can be used, such as slack wax which containsabout 10 to 40 Wt. percent mineral oil and generally has a melting pointbe-' tween about 115 and 160 F., and scale wax which contains about 0.5to 4 wt. percent mineral oil and has a melting point between about 125and F. Correspondingly, petrolatum can also be used. Petrolatum is acrude microcrystalline wax usually containing about 10 to 40 wt. percentmineral oil and generally having a melting point of about 120 to F. Anumber of emulsifiers can be used to make the emulsion. One type ofemulsifier which was found par ticularly effective is the fatty acidpartial ester of an aliphatic polyhydric alcohol. These partial estersinclude the C to C fatty acid partial esters of aliphatic polyhydricalcohols having about 3 to 12, e.g. 3 to 8, carbon atoms, and about 2 to8, eg 3 to 6, hydroxy groups per molecule. Preferred materials are themonoand'diesters of C to C fatty acids. The above type of partial estersincludes the partial esters of monodehydrated aliphatic polyhydricalcohols, which are well known in the art, of example, see US. Patent2,434,490, as well as partial esters of non-dehydrated aliphaticpolyhydric alcohols, e.g. pentaerythritol monooleate.

Specific examples of the above types of partial esters will include:glyceryl monooleate, pentaerythritol monooleate, sorbitan monooleate,the dioleates of sorbitan, mannitan, pentaerythritol and relatedpolyhydric alcohols, the corresponding partial stearic and palmitic acidesters of these alcohols, and partial esters of these alcohols made frommixturesof these fatty acids.

Also partial esters of the above type can be further H reacted withalkylene oxide such as ethylene oxide, propylene oxide, etc. toincorporate about 1 to 30 alkoxy .groups into each partial estermolecule. Alkylene oxide treated materials of the above type are wellknown and have been described in detail in US. Patents 2,374,931

F. These waxes will generally contain from 0.2 to 40 wt.,

percent, preferably 0.2 to 25 wt. percent of mineral oil.

Waxes of the above description include refined parafiin wax generallyhaving about 0.1 to 0.5 wt. percent mineral oil and consistingessentially of straight chain alkaline of 16 to 50 carbon atoms, andgenerally melting in the range of about 110 to F.

Waxes of the above description also include the socalledmicrocrystalline waves which are obtained as byproducts from thedewaxing of heavy mineral oil stocks, such as heavy lubricating oildistillate, cylinder oils, bright and 2,380,166.

Other useful. classes of emulsifying agents including non-ionic andcationic surface active agents which will emulsify the wax of thegeneral formula:

R[( )x y wherein R is an aliphatic hydrocarbon radical having 2 to 4carbon atoms; x is an integer of 5 to 200, e.g. 5 to 75; and y, which iseither 1 or 2, is the valence of R; while R .is a radical selected fromthe group consisting of: HO-;

the wax residue of the dried-out emulsion. Because of thisre-emulsifying feature, the forms are readily cleaned after use byrinsing or washing with water. However, in some instances itis preferredto use an emulsifier which will not re-emulsify the wax once theoriginal water content has evaporated. Thus, for casting outdoors, toavoid the effect of rain wash-off of the dried emulsion, suchnon-re-ernulsifying agents are preferred. A very desirable class of suchagents are salts of C to C fatty acids with volatil amines Such 'asammonia, morpholine, monoethanolamine, triethanolarnine, etc, Thesesalts are made ,by simple mixing of the fatty acid and the amines. The

addition products or salts can be prepared directly in the emulsionmixture at the time of emulsification. I Specific examples of such saltsare the stearic acid salt of morpholine; triethanolamine stearate;ammonium laurate; ammonium stearate; etc.

Various. Other additive materials may also be ncluded in thecompositions of the invention in amounts of about 0.0002 to 10.0 wt.percent each, based on the total weight of the composition. Suchadditives include: additives used in the wax to pr ven oxidatio of thewax wh in st age prior to manufacture of the. emulsion; additives foraiding stabili y f the m lsion su h as gums, methyl or gether to atemperature about 20 F. above the melting point of the wax and slowlyadding water at approximately the same temperature while agitating sothat phase inversion of the emulsion occurs. That is, the emulsionchanges from a water-in-hydrocarbon emulsion to a hydrocarbon-in-wateremulsion system. Mechanical homogenization also may be used ifnecessary, to improve the dispersion, making a very uniform stabledistribution of fine particles of emulsified wax. The concentrate canthen be diluted at room temperature with additional water by simplemixing, prior to the actual application of the emulsion. The finaldiluted product can be applied to the mold forms by mopping, swabbing,spraying, dipping, brushing, rolling; etc. Spraying is generallypreferred, using either a hand or blower operated spray, to obtain auniform and economical coating. In any event, the compositions of theinvention are applicable by any of the above methods. After the waxemulsion is applied to the form, it is allowed to dry by evaporation ofthe water to leave a coating of wax on the form surface. After drying,the form is then used to mold concrete.

In general, the wax emulsions of the invention are easy to apply, willadhere well to all form surfaces including vertical and invertedmembers, will not permanently stain concrete surfaces and do not leaveresidues that will interfere with further treatment, e.g. painting, ofthe concrete surfaces, They will also permit easy break-away of the formfrom the hardened concrete, will waterproof wooden and otherwater-absorbent forms to thereby permit their repeated use, and willgenerally inhibit rusting of steel forms and metal equipment.

The invention will be further understood from the following exampleswhich include a preferred embodiment of the invention.

The physical properties of the waxes used in preparing the examples ofthe invention are summarized in Table I, which follows:

TABLE I.-.INSPEOTIONS OF WAX STOCKS Parafiin Paraffin Slack Slack SlackParaffin Wax I Wax II Wax III Wax, IV Wax V Wax VI Melting Point, F.(AS'IM D- 127' 124 130 150 118 131 123 Oil Content, percent (ASTM 13-7210.2 t). 3 23 23 23 0.2 Viscosity at 210 F., cs. (ASTM ethyl cellulose,carboxy vinyl compounds (e.g. Carbopol 941), fatty alcohols, gelatinsand the like; additives for prevention of bacteria or fungus growth inthe'emulsion 60 wt. percent of the wax. These concentrates can then bereadily cut back with additional water to form final compositionscontaining about 2 to wt. percent wax, and preferably 5 i9 25 Wt.percent wax. The concentrates are readily prepared by heating the waxand emulsifier to- Paraffin Wax I was prepared from a contiguous-boilingwaxy distillate lubricating oil stream, refined by conventional solventcrystallization, filtration, hydrogen treating and bauxite percolationprocesses.

Paraffin Wax II was prepared from a mixture of two separate slack waxesfrom non'contiguous, waxy lubrieating oil distillate streams. That is,the mixture of slack waxes (Paraffin Wax II) were prepared from SlackWax IV and Slack Wax V. The mixed Slack Waxes IV and V were processedtogether through the conventional processes of solvent crystallizationto reduce the oil content, filtration, hydrogen treating and bauxitepercolation.

Slack Wax III was prepared from a moderately high boiling lubricatingoil distillate stream by conventional processes of dewaxing saiddistillate stream by solvent crystallization.

Paraflin Wax VI was prepared by a method of manufacture similar to themethod of preparing Paraffin Wax 1.

EXAMPLE I Three concentrates, designated A, B, and C were pre- 6 (d)Rusting of the form, i.e. the degree of rust that resulted on the panelduring the test.

The compositions tested and the results obtained are summarized infollowing Table III.

TABLE III.-EVALUATION OF WAX EMULSION RELEASE AGENTS Treated PanelUntreated Panel Commercial Emulsion Concentrate A Emulsion Concentrate BEmulsion Concentrate C Oil Baise gen Dilution ratio, water to 2/1 4/12/1 4/1 2/1 4/1 Undiluted.

emulsion concentrate.

Form break-away V. diflicult Good Good Good Good V. easy V. easy V.easy. Concrete holdover Appreciable amt Slight Slight Shght Sl ght V.slight V. slight Slight. Form clean-up... V. diificult Wipes 011...Wipes ofi Wipes 01in. Wipes 011... V. easy V. easy Wipes ofi. Busting ofform Slight to heavy Slight Slight Noue..... V. shght.-- Slight SlightNone.

The form is cleaned for re-use by washing, wiping or brushing to removeadhering cemens particles from previous casting.

pared. These compositions are given by weight: TABLE II.COMPOSITION OFWAX EMULSION CONCEN- TRATES USED IN LABORATORY CONCRETE MOLD RE- LEASEEVALUATIONS in Table II in parts Concentrate Composition (wt. percent) AB C Paraflin Wax I Parafiin WaxII Slack Wax III.

Span 60 (Sorbitan monosteai'ate) Tween 60 (polyoxyethylene sorb anmonostearate) Stearic Acid Morphnline Water Tris Nitroi o. 04 0. 00 o.04

mogenized and the fungicide was then added. Concentrate B was formed ina similar manner except that the morpholine was dissolved in the waterand the stearic acid in the wax in separate vessels, each solution beingmade at a temperature of about 155 F., the emulsion was then made byadding the wax phase to the water phase, with stirring, followed byhomogenization under high shear conditions.

The Span 60 and Tween 60 are commercial emulsifiers and are of thepartial ester type and the all cylene oxidetreated partial ester typerespectively. The Tween 60 averages about oxyethylene groups permolecule. The Span 60 and Tween 60 are 100% active ingredient.

The Emulsion Concentrates of Table II were diluted by simple mixing withadditional water, and the diluted emulsion was then applied to cleansteel panels by dipping, then allowing the panels to drain and dry. Atubular cylinder was set on each of the dried panels and wet concretewas poured into the cylinder and allowed to harden.

The cylinder with the hardened concrete was then removed from the panel.For comparison, concrete was also cast with the cylinder on untreatedsteel panels. Also, for comparison, tests were made using a commercialmold release agent. In each case, the area of contact between the steelpanel and the concrete was graded for:

(a) Form break-away, i.e. the ease of separating the steel form or panelfrom the hardened concrete coating.

(b) Concrete holdover, i.e. the relative amount of concrete adhering tothe separated steel panel.

(0) Form clean-up, i.e. the ease of cleaning the separated steel panel.I

forcing bars are in the flat section of the slab. The steel As seen fromTable III, the emulsions of the invention performed very well in alltests and compared well with the commercial oil base agent which wasused in an undiluted form. From an economic standpoint, the waxemulsions (diluted in a 4:1 ratio) will have a selling price on theorder of about one-sixth of the selling price of the oil base commercialagent which is used without dilution. Emulsion Concentrate C of TableIII gave particularly good results in that the form break-away was very(V.) easy with very slight concrete holdover, while form cleanup wasalso very easy. On the other hand, the completely untreated panel wasvery diificult to break-away from the hardened concrete, the amount ofconcrete adhering to the untreated panel was appreciable and theclean-up of the untreated panel was very difficult.

A composition of the invention was prepared and used in actual fieldtests. This composition was made by dilution of a concentrate having thefollowing formulation:

Concentrate D was prepared in the same manner as Concentrates A and C ofExample I.

Steel forms for molding two bridge slabs and thirtysix piling sectionswere coated with Concentrate D diluted with 4 parts of water. Thediluted wax emulsion was sprayed from a 45 gallon tank with 50 p.s.i.air pressure through long A hoses and spray nozzles at a rate of 300 sq.ft. per gallon on the slab forms and 600 sq. ft. per gallon on thepiling forms. The bridge slabs were molded in wax emulsion coated webshaped steel forms, with the top finished to a roadway surface, 30 ft. x60 ft. The webs were 4 ft. in depth and the slab weights wereapproximately tons. Steel cables stressed at 160,000 p.s.i. are in thelower concrete web. A net-work of heavy steel reinforms haveapproximately 5,000 sq. ft. of surface that were ,coated with the waxemulsion. The sides of the steel form webs are retractable with a screwmechanism. The concrete sq. pilings are cast around steel cablesstressed to 160,000 p.s.i. and a net work of reinforcing bars and wire.The piling has a round hollow core which was formed by casting around awax/plastic coated fiber pipe equal to about /2 the volume of the totaldimensions of the finished piling. The concrete was poured intocollapsible 3-sided steel forms which vary in size from 12" to 30"widths and 10 to 40 ft. lengths. In the preceding tests, a day was spentin pouring th concrete and another day in steam curing of the concreteunder plastic covers. The third day was spent in TABLE IV.CONCRETECASTING USING WAX EMULSIONS Concrete Roadway Concrete Square BridgeSlabs Pilings 30 it. X 60 it. x 4 It.

Size of casting Up to 30 inches sq. x

web depth. 110 it. length. Number of castings. Two Thirty-six. EmulsionCon- D D.

ccntrate used.

Dilution ratio 4 parts Water, 1 part 4 parts water, 1 part with water.emul. cone. D. emul. cone. D. Application Rate 300 sq. ft. per gallon600 sq. it. per gallon of diluted wax of diluted wax emulsion. emulsion.Form removed Easy asy. Appearance of east Excellent Excellent.

concrete surface. Concrete holdover Very little Very little.

on form. Form clean'up Excellent Excellent.

EXAMPLE III Emulsion Concentrate E was prepared in the same generalmanner as Emulsion Concentrate B of Example I. The composition andproperties of Emulsion Concentrate E are summarized in Table V whichfollows:

TABLE V.--EMULSIO-N CONCENTRATE E Composition (wt. percent):

Slack Wax similar to Slack Shelf stability No separation at 40, 73 and125 F. after 1 month.

Satisfactory.

Carbopol 941 is a water-soluble thixotropic thickeneremulsifier used toimproved shelf stability. It is a carboxy vinyl polymer and is suppliedas an acid in a dry powder form. Neutralization increases the viscositysharply. For this reason the Carbopol must be completely dissolved inthe water before morpholine is added and before the emulsion is made.Carbopol may be used in any of the anionic emulsions at 0.01 to 0.05 wt.percent without otherwise modifying the formula. A concentration of 0.02wt. percent is usually most suitable.

The Emulsion Concentrate E can be diluted with 2 to 4 times its volumewith water and used in the manner illustrated by Examples I and II.

In many applications, the quick breaking Dilution with hard Watercharactertistics of the anionic emulsion, such as that of EmulsionConcentrate E will be of value. These emulsions are considerably moreresistant to re-dispersion or wash-E than the nonionic emulsionsrepresented by Emulsion Concentrates A, C and D. In addition, theanionic emul sions are less subject to bacteria and fungi attack, andare more stable undiluted. On the other hand, the nonionic emulsionshave better tolerance for hard water; i.e., the nonionic emulsionsremain better dispersed in solutions of metal ions, acids and bases.These points are compared in Table VI which follows:

TABLE VI.GENERAL COMPARISON OF NONIONIC AND ANIONIO WAX EMULSIONCHARACTERISTICS Low sensitivity to divalent metal ions, hydroxyl, andhydrogen ions.

High dilution (10% wax) remains dispersed without stirring.

Dried films sensitive to water (slough off or redisperse).

Subject to attack by bacteria and fungi unless fortified with Sensitiveto water hardness above 250 p.p.m. to Varying degrees. Dilution with1000 p.p.m. hard water is an upper limit.

Not redispersable after drying.

Fungi and bacteria attack is controlled by morpholine.

bactericide-iungicide additive.

What is claimed is:

1. A method for the treatment of forms for molding of concrete toprevent sticking of concrete to said forms and to permit the removal ofsaid forms from hardened concrete, which comprises applying to saidforms a wax emulsion release agent consisting essentially of watercontaining about 2 to 40 wt. percent of a petroleum wax and about 0.1 to5.0 wt. percent of an emulsifying agent, all of said wt. percent beingbased upon the total weight of said release agent, and allowing saidrelease agent to dry whereby the water evaporates to leave a solid waxyfilm on said forms.

2. A method according to claim 1, wherein said emulsifier is a C to Cfatty acid partial ester of a C to C aliphatic polyhydric alcohol having2 to 8 hydroxy groups per molecule.

3. A method according to claim 1, wherein said emulsifier is an alkyleneoxide treated partial ester of a C to C fatty acid and a C to Caliphatic polyhydric alcohol having 2 to 8 hydroxy groups per molecule,wherein the number of alkylene oxide groups incorporated per molecule ofsaid partial ester is about 1 to 30, and said alkylene oxide is a C to Calkylene oxide.

4. A method according to claim 1, wherein said emulsifier is a salt of aC to C fatty acid and a volatile amine, which salt will decompose uponevaporation of said water to prevent re-emulsification of said wax.

5. A method according to claim 1, wherein said emulsifier is sorbitanmonooleate.

6. A method according to claim 1, wherein said emulsifier is sorbitanmonostearate alkoxylated with about 20 oxyethylene groups per molecule.

7. A method according to claim 1, wherein said emulsifier is a salt ofstearic acid and morpholine.

8. A method according to claim 1, wherein said wax is a petroleum waxhaving a melting point of to 185 F. and a mineral oil content of 0.2 to40 wt. percent.

0. A method according to claim 1, wherein said wax is a refined paraffinwax having a melting point of about to 165 F. and containing about 0.1to 0.5 wt. percent mineral oil.

10. A method according to claim 1, wherein said wax is a slack waxhaving a melting point of about to F. and a mineral oil content of 10 to40 wt. percent.

11. A method of molding concrete shapes in metal forms designed forreuse which comprises applying to said forms a wax emulsion releaseagent consisting essentially of water containing about 2 to 40 wt.percent of a petroleum wax and about 0.1 to 5.0 wt. percent of anemulsifying agent, all of said wt. percent being based upon the totalweight of said release agent, allowing said release agent to dry wherebythe water evaporates to leave a solid waxy film on said forms, pouringwet concrete into said forms, allowing said concrete to harden and thenremoving said forms from said concrete after said concrete hardens.

References Cited UNITED STATES PATENTS Edwards 106-38.22 Grifiin 106-271Grupelli 264-438 Snyder 106-38.25 Sesso et a1. 106-271 Cross 106-271Henry 106-38 Dieman et a1. 106-271 Miesel 106-38.23 Rudel et a1. 106-271Tillman 106-243 Rockland 106-271 Sheldahl et a1. 106-271 FOREIGN PATENTSGreat Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner. 10 MORRIS LIEBMAN, Examiner.

J. B. EVANS, Assistant Examiner.

1. A METHOD FOR THE TREATMENT OF FORMS FOR MOLDING OF CONCRETE TOPREVENT STICKING OF CONCRETE TO SAID FORMS AND TO PERMIT THE REMOVAL OFSAID FORMS FROM HARDENED CONCRETE, WHICH COMPRISES APPLYING TO SAIDFORMS A WAX EMULSION RELEASE AGENT CONSISTING ESSENTIALLY OF WATERCONTAINING ABOUT 2 TO 40 WT. PERCENT OF A PETROLEUM WAX AND ABOUT 0.1 TO5.0 WT. PERCENT OF AN EMULSIFYING AGENT, ALL OF SAID WT. PERCENT BEINGBASED UPON THE TOTAL WEIGHT OF SAID RELEASE AGENT, AND ALLOWING SAIDRELEASE AGENT TO DRY WHEREBY THE WATER EVAPORATES TO LEAVE A SOLID WAXYFILM ON SAID FORMS.
 11. A METHOD OF MOLDING CONCRETE SHAPES IN METALFORMS DESIGNED FOR REUSE WHICH COMPRISES APPLYING TO SAID FORMS A WAXEMULSION RELEASE AGENT CONSISTING ESSENTIALLY OF WATER CONTAINING ABOUT2 TO 40 WT. PERCENT OF A PETROLEUM WAX AND ABOUT 0.1 TO 5.0 WT. PERCENTOF AN EMULSIFYING AGENT, ALL OF SAID WT. PERCENT BEING BASED UPON THETOTAL WEIGHT OF SAID RELEASE AGENT, ALLOWING SAID RELEASE AGENT TO DRYWHEREBY THE WATER EVAPORATES TO LEAVE A SOLID WAXY FILM ON SAID FORMS,POURING WET CONCRETE INTO SAID FORMS, ALLOWING SAID CONCRETE TO HARDENAND THEN REMOVING SAID FORMS FROM SAID CONCRETE AFTER SAID CONCRETEHARDENS.